Reusing of Alkaline Red Mud as Self-supplied Electrolyte and Positive Active Material for Aqueous Supercapacitors

Abstract

Red mud (RM), as an industrial waste in the bauxite industry, has long been threatening environmental resources such as land and rivers due to its high alkalinity and corrosiveness. In recent years, the application of RM in various fields to invigorate it has been constantly explored. In this study, we report reusing of alkaline RM as self-supplied electrolytes (aRMS-electrolyte) and positive active material for aqueous supercapacitors. We designed three different structures of supercapacitors RM(+)/aRMS-electrolyte/AC(-), AC(+)/aRMS-electrolyte/RM(-), and RM(+)/aRMS-electrolyte/RM(-). The electrochemical results show that RM(+)/aRMS-electrolyte/AC(-) has a remarkable current response, lower interface charge transfer resistance and the ion diffusion resistance, and larger specific capacity (13.8 mF/g for RM(+)/aRMS-electrolyte/AC(-), 9.0 mF/g for AC(+)/aRMS-electrolyte/RM(-) and 9.8 mF/g for RM(+)/aRMS-electrolyte/RM(-) at 0.2 mA/g). The unique feature of this work lies in: (1) The electrolyte is entirely derived from the dissolution of the base in the RM; (2) Raw RM is directly applied to supercapacitors without any pretreatment, which is a very simple and straightforward solution. (3) The transformation from industrial waste to electrode materials has achieved high value of RM. (4) The discovery of the adsorption behavior of AC for Na+ in electrochemical systems has opened up the possibility of enriching sodium element from RM. In conclusion, this work has explored a possible path for the high value utilization of RM and the construction of new type supercapacitors.

Affiliated Institutions

• Liaocheng University CN

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